SPRINGFIELD — The story of how state Senator Eric Lesser will celebrate Passover in the White House with President Obama Friday begins where few grand tales do: in a dim basement room of a Sheraton in Harrisburg, Pa.

During the Pennsylvania primary, one of the toughest patches of the 2008 presidential contest, Lesser and other Obama campaign aides organized an impromptu Passover Seder there and were joined by a surprise guest. In the years since, the President, who is Christian, has not only brought the yearly ceremony to the White House, but makes a point of participating and including Lesser and other members of the original crew.

So Lesser, after doing the mundane work of a backbench legislator this week — huddling with staff about the closure of a small bridge, talking with a constituent about arts programs, fielding budget queries — will head to Washington and is set to break bread, matzo, with the commander-in-chief in another chapter of an unlikely story.

For Lesser, 30, the annual Seder serves as a marker of his life’s rapid progression from young campaign aide to Massachusetts’ youngest state senator, now married, with a daughter.

At the 2009 Seder, the first one in the White House, he was single and brought his father to the dinner. At the time, he was working as the special assistant for David Axelrod, Obama’s senior adviser and strategist.

In 2011, Lesser was working for the President’s Council of Economic Advisers and brought Alison Silber, his then-fiancee. She was his guest again in 2012, months after they were married, and when he was a first-year Harvard Law School student.

And in 2014, amid Lesser’s state Senate campaign, the Longmeadow couple brought along their young daughter, Rose.

After the president, first lady, and about 20 guests worked their way through a Haggadah, the Passover service text, some of the dinner discussion turned to a certain Springfield-area election.

“At one point, the president started asking him about how the campaign was going,” said Newton native Herbie Ziskend, one of the young coorganizers of the original Seder and an attendee every year since.

“It felt a little bit like getting pee-wee football coaching from Tom Brady,” Lesser said in Springfield this week. “But he is a former state senator himself. He is familiar with how a state senate campaign operates.”

Lesser said Obama told him to knock on every door and talk to as many people as he could one-on-one. (Lesser ended up winning the open seat in a district that includes some of Springfield and Chicopee and seven nearby towns.)

The elegant presidential surroundings are a far cry from the group’s original Seder in 2008.

That year, in the midst of the tough Democratic primary campaign in Pennsylvania, it wasn’t practical for Lesser, Ziskend, and Arun Chaudhary, another Jewish staff member, to get home for the holiday, which commemorates the Israelite exodus from slavery in Egypt. So they threw together a Seder — with some emergency supplies, including matzo and kosher wine, procured by Lesser’s cousin in Philadelphia — and held it in the basement of a Sheraton in Harrisburg, Pa., in what Ziskend called “a little dark, not-that-nice room.”

It was originally going be just the three of them and a few other staff members. But then-US Senator Obama and others ended up joining.

The 2008 Seder ended, as many traditional Seders do, with the attendees raising their glasses and saying, in unison, “Next year in Jerusalem!” And then Obama added, “Next year in the White House.”

And so it was that the custom begun in Pennsylvania continued at 1600 Pennsylvania Avenue.

It has evolved a bit. In 2011, for instance, the attendees began reading the Emancipation Proclamation at the end of the Seder, in a nod to the universal message of a holiday that celebrates freedom from bondage.

On Friday, coorganizers Lesser (2008 Seder: luggage wrangler; now: state senator), Ziskend (2008: advance man; now: a director at an investment firm) and Chaudhary (2008: Obama’s videographer; now: a creative director at political communications firm) are set to return to the White House.

Beforehand, the three, who all worked in the administration during Obama’s first term, will huddle to practice helping to lead the evening’s activities.

“Eric leads us in the songs,” Chaudhary explained. “He and I do a lot of the explaining and traffic management, and Herbie does the holding up of stuff, like on the Seder plate.”

White House chefs do the cooking, including using some family recipes from participants. Last year’s menu included Passover foods such as gefilte fish, chicken soup with matzo balls, and kugel.

The Seder tradition is anchored in the retelling of the Exodus story. And for Lesser, retelling his own Passover story — how he came to celebrate with the president himself — has become something of a touchstone.

Earlier this week, Lesser regaled sixth-, seventh-, and eighth-graders at Heritage Academy, a Jewish community day school in Longmeadow, with his real-life tale of being part of history in 2008.

State Senator Eric Lesser, a Longmeadow Democrat, thanked students at Heritage Academy in Longmeadow for giving him a Seder plate on Tuesday.

Matthew Cavanaugh for The Boston Globe

He told them about campaign staff members, Jewish and not, making their way into the basement room. Just as they were about to start the service, they heard a familiar voice from the hallway.

“He popped his head in and said, ‘Hey, is this where the Seder is happening?’ And it was Barack Obama,” Lesser recalled.

Lesser, who is still a Harvard Law School student, explained how the tradition has continued and, in 2009, they “celebrated the first Seder in the White House in American history.”

He also chronicled that time the Seder was delayed when a participant had trouble getting a container of macaroons past the Secret Service. And talked about Malia and Sasha Obama usually finding the afikomen, a hidden piece of matzo that is a part of the Passover service.

The middle-schoolers were enthralled, peppered him with questions, and then presented him with a note and a decorated Seder plate to bring to the First Family.

He assured them he would deliver the items on Friday when he shows up at the White House, where the event is expected to be essentially the same.

But for one notable change.

“For an apolitical event,” Chaudhary said, “it’s ironic but very cool to have two elected officials there now.”

By which he meant: the leader of the free world and state Senator Eric Lesser.